Progress: The number of recommended projects has been met and progress is being made, but further work is needed to understand how autism develops. Some recent data suggest that regression may be more of a continuum than a distinct type of autism, and several studies have provided new descriptions of ASD developmental trajectories. However, other studies have found some differences between children with reported regression vs. children without reported regression.

Remaining Gaps, Needs and Opportunities: Further work is needed to better understand subtypes and potential biomarkers. High-risk siblings may present an opportunity for studying regression prospectively.